feat(flamegraph): Use average frame duration in call tree table view

[Zylphrex]

The sum frame duration is not a useful metric without an idea of how frequently it's called. This swaps it out for avg frame duration. Would be better to have the number of calls as well but that's out of scope of this PR.

Closes PRO-25

[linear]

PRO-25 aggregate call trees should show average duration instead of sum

[codecov]

✅ All tests passed

[JonasBa]

The sum frame duration is not a useful metric without an idea of how frequently it's called.

I'd be curious to compare a few side by side and see which one surfaces the data more accurately. The reason I say this is because I am afraid that averages will hide outliers, and outliers are super important in the context of performance investigations.

Call frequency is not something we can accurately compute, but it would be great to expose like you said. I think we should let the user decide here, and make this configurable. Average seems like a sensible default and something that will work for most folks, but adding columns or changing what values they show could enable different types of investigations or views into the data

[Zylphrex]

@JonasBa Yeah we don't have any accurate way of computing call frequency even on the backend today. The response currently contains the call frequency in the scope of the computed flamegraph but that's not super useful to expose for the similar reasons why sum of durations isn't useful to expose.

And while average does indeed hide high outliers, we don't actually have any way to identify them to begin with so that's a future problem like you said.